HTML Signature format

User's guide:

Hyper Text Markup Language (HTML) files must have a signature (tag) <html> somewhere at the beginning of the document.
Another tag <head> is usually present in HTML document and it contains web page title, encoding, keywords, scripts and other meta-data.
HTML file does not have pre-defined internal structure and data fields, including file size.
If HTML document is properly formatted, the closing tag </html> should also be present, and it points to the file and data end.

When inspecting example.html file's text data using any Hex Viewer, like Active@ Disk Editor we can see it starts
with a tag <html (hex: 3C, 68, 74, 6D, 6C). Next to it there is a tag <head> (hex: 3C, 68, 65, 61, 64, 3E).
Final signature </html> (hex: 3C, 2F, 68, 74, 6D, 6C, 3E) can be found at offset 285.
Thus total file size is 285+7=292 bytes, and reading of all 292 consecutive bytes starting from the position of detected <html
header provide us with all HTML file data, provided that file is not fragmented.